Sam Querrey needed two tie-breaks to prevail against Benjamin Becker, as the American booked his place in the second round of the Rosmalen Grass Court Championships.
As the grass-court season got under way at this ATP 250 event, fifth seed Querrey found himself in a tough tussle with world number 116 Becker.
Querrey fought back from 3-0 down in the first-set tie-breaker and 3-1 behind in the second to eventually come through 7-6 (7-3) 7-6 (7-5).
Defending champion and eighth seed Nicolas Mahut also progressed, although he had a more straightforward test, getting the better of qualifier Lukas Lacko 6-1 6-4.
Mahut will now meet Paul-Henri Mathieu, who eased beyond Rajeev Ram 6-4 6-4.
Great Britain's Aljaz Bedene is also through and will meet second seed Bernard Tomic after seeing off Ernesto Escobedo 7-6 (7-5) 6-2, while wild card Stefan Kozlov overcame Yoshihito Nishioka 6-1 2-6 6-3.